The abrasive grain portion of the majority of vitreous-bonded grinding wheels in commercial use is composed of either fused aluminum oxide or silicon carbide. Those skilled in the art of grinding select silicon carbide as the preferred abrasive when the object to be ground is titanium, a super alloy, a low-tensile ferrous alloy, or a nonmetallic such as stone, ceramic, or glass. Similarly, those skilled in grinding select fused aluminum oxide for grinding steels, hardened or soft.
The use of mixtures of silicon carbide abrasive grains with fused aluminum oxide abrasive grains in the manufacture of grinding wheels and other abrasive bodies is known in the art and produces a product with properties intermediate to either abrasive type used singly. Such mixed abrasive type wheels are used where a single wheel must grind a wide variety of materials and need not be optimum for any single material. The grinding performance is usually intermediate between that of either abrasive type used alone.